Discussing and Treating Iron Gall Ink

tslacarchives

2 years ago

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This summer, TSLAC Conservation participated in an informal learning series called Thinkery21. Hosted at the Thinkery (formerly the Austin Children’s Museum,) Thinkery21 invites adults to visit the museum after hours to explore a variety of science- and arts-related programming. The evening, titled “Inkery,” offered talks and demonstrations about ink and printing.

While participants made iron gall ink a few feet away, TSLAC Conservation discussed the prevalence and challenges of iron gall ink in archives. We examined photographs of famous Texas documents written with iron gall ink, including the Travis Letter and the Texas Declaration of Independence. We also tested visitors’ newly made ink with indicator paper to look for excess iron ions. These ions point to accelerated future degradation. At this point, many concerned participants asked, “But what can you do?”

This excellent question has driven significant conservation research for many years. Left untreated, iron ions from iron gall ink will break the chains of cellulose that compose paper. This causes the paper to become brown, brittle, and prone to break. In extreme cases, inked areas can completely drop out of the paper.

This treaty on Texas Comanche affairs shows advanced iron gall corrosion. Large sections of the “G” have completely dropped out of the paper.

One response increasingly used by our lab is to treat the document with calcium phytate. This treatment employs a principle called chelation. During chelation, the calcium phytate locks up the dangerous iron ions so they can’t attack the paper. This is much the same process as when a person takes antioxidants to block free radicals in his or her body. Although the iron ions are still present, they no longer threaten continuing damage to the treated document.

TSLAC Conservation was pleasantly surprised that the Thinkery21 merrymakers were so receptive to a (brief) lecture on paper chemistry! We hope the event provided a useful window onto the surprising complexities of ink on paper.